1. Field of the Invention
This invention relates generally to wireless networks and, more particularly, to a methodology and a concomitant system whereby a cell-phone in a roaming area is configured with the operational characteristics of a local cell-phone while in a roaming area.
2. Description of the Background Art
Roaming of cell-phone users in areas covered by different network operators is possible because of roaming agreements between the various cellular system operators. If a cell-phone with home network A is to be used in network B, then a roaming agreement between the operators of networks A and B is necessary. When the cell-phone is taken into the coverage area of network B, it is registered and calls to and from it are allowed by a mobile switching center of network B. Later, the call charge incurred by the cell-phone while it was roaming under network B is settled with the billing authority of network A. Generally, the cost of calls incurred by a cell-phone is higher when it is being used in a visiting network area. Such costs are significantly higher when roaming area is in a distant country other than the home country of the cell-phone. It is desirable to minimize the cost of calls while roaming in an area other than the home location. Keeping this in view, a method of minimizing call costs in a roaming area by dynamically changing the identity of the cell-phone to behave like a local phone is described in this invention.
As the subject matter in accordance with the present invention involves the programming of the Subscriber Identification Module (SIM) used in the Global System for Mobile (GSM) systems, relevant details of the SIM required for understanding the embodiments of this invention are now given.
The specification of GSM, the European Digital Cellular System for Land Mobile Radio Communications, defines that all the information elements needed by a radio system to identify, authenticate and locate a mobile subscriber will be contained in a dedicated SIM module, which is removable and can be used in different mobile stations. The remaining part of the mobile station, called a mobile equipment (ME), is intended to contain all the mechanisms and devices which are needed to access the GSM services (for instance, the radio equipment) but are not specific to a given subscriber. Furthermore, the SIM is removable from the mobile equipment and the interface between the subscriber identity module and the mobile equipment is standardized in ETSI specification GSM 11.11. This interface is in accordance with ISO standards on IC cards (ISO 7816).
As noted above, GSM systems use a SIM-card that stores user identities and other user specific information and thereby enables access to the service of the radio system. Only a combination of the SIM and the ME makes an operative mobile station (MS) for GSM system. The same SIM card may be used in any GSM mobile equipment ME.
Representative of art pertaining to the inventive subject matter is U.S. Pat. No. 5,657,373 (""373) issued to Hermansson et al and entitled xe2x80x9cDigital mobile telephone system in which each subscriber is assigned a telephone number and several subscriber identity module (SIM) cards.xe2x80x9d In ""373, a digital mobile communication system comprises a switching center (MSC), a subscriber register (HLR) connected thereto, mobile terminals, such as mobile telephones, and subscriber-linked subscriber""s cards, such as smart cards. Each subscription is allocated a subscriber""s number and at least two subscriber""s cards are adapted to be activated so as to open a mobile terminal to incoming as well as outgoing traffic when inserted therein. When one of the subscriber""s cards is activated, the other card or cards are necessarily deactivated so as to open a mobile terminal only to outgoing traffic when inserted therein. The subscriber register (HLR) is adapted to control the activation and the deactivation of the cards by the order of the subscriber. This reference ""373 has the shortcoming of requiring the user to change the SIM cards for activation of a mobile telephone to operate with the other SIM cards. Moreover, the additional SIM cards are not usable by other users. Such a method is not suitable for roaming users, as they have to obtain the SIM cards for each of the roaming areas they plan to visit.
Thus the art is devoid of a generic method of minimizing call costs in a roaming area by dynamically changing the identity of the cell-phone to behave like a local phone.
These shortcomings and other limitations and deficiencies are obviated in accordance with the present invention by a method, and concomitant circuitry, to register a roaming phone in a visiting location as a local phone.
In accordance with the broad method aspect of the present invention, a method for operating a roaming cell-phone includes: (a) determining roaming-related information from the roaming cell-phone in a roaming area; and (b) dynamically configuring the roaming cell-phone to operate as a local cell-phone in the roaming area with reference to the roaming-related information.
In accordance with yet another broad method aspect of the present invention, a method for operating a roaming cell-phone includes: (a) registering the phone using home roaming-related information about the cell-phone in a roaming area; and (b) dynamically re-registering the phone using local roaming-related information for the cell-phone in the roaming area with reference to the home roaming-related information.
In accordance with still another broad method aspect of the present invention, a method for registering a roaming cell-phone as a local cell-phone includes: (a) identifying a roaming service provider node serving the roaming cell-phone; (b) sending to the roaming service provider node from the roaming phone a message containing cell-phone identification information about the roaming phone; (c) transmitting to the roaming phone from the roaming service provider node a response message containing a local number for establishing a call between the roaming phone and a visiting location mobile switching center; (d) communicating the local number to the visiting location mobile switching center from the roaming phone; and (e) enabling the roaming phone to operate as a local cell-phone in the visiting location with the local number.
In accordance with a broad system aspect of the present invention, the system for operating a roaming cell-phone comprises: (a) means for determining roaming-related information from the roaming cell-phone in a roaming area; and (b) means for dynamically configuring the roaming cell-phone to operate as a local cell-phone in the roaming area with reference to the roaming-related information.